An airport shares real time information with arriving and departing aircraft over many communication channels. Voice communication is widely used to communicate weather information such as visibility, wind speed and direction, precipitation, and atmospheric pressure, used to set an aircraft's altimeter. Weather information may be recorded or automated and repeatedly broadcasted on the automatic terminal information service (ATIS). An airport may have a voice radio channel dedicated to the ATIS for that airport. An airport also uses voice communication to tell a departing aircraft which taxiway and runway to use while on the ground and may also communicate potential hazards in the area, such as ground vehicles or animals. Air traffic control may use voice communication for aircraft approaching for landing to direct aircraft movements into a landing pattern, instruct which instrument approach to use, instruct which runways to use, and for providing other such directions. With voice communications, only one person may speak at a time for a given channel, resulting in limited bandwidth, especially at busy airports or during emergencies.
Other real-time communication channels include high speed communication links such as broadband and satellite. Although efficient, current communication links suffer from challenges such as limited coverage area, periodic unavailability of communication link, and increasing demand for bandwidth in today's aircraft. Factors important in communication links include data speed, cost, and reliability of the communication link. In some examples, flight data may be shared between aircraft using ground systems because of the high bandwidth requirements.